题目选项分析

Public health official: Some researchers suspect that magnetic fields from high-voltage power lines can cause health problems for people who live especially near the lines. However, this is extremely unlikely: beyond a distance of a few feet, the strength of the magnetic fields from high-voltage power lines is less than the average strength of magnetic fields in homes that are not located near such lines.

Which of the following would it be most useful to establish in order to evaluate the public health argument?

【选项】What is the average strength of magnetic fields in workplaces that are not located near high-voltage power lines